1. Field of the Invention
The present invention relates to a method and an apparatus for managing power of a Wireless Local Area Network (WLAN) module in a portable terminal. More particularly, the present invention relates to a method and an apparatus for managing power of a WLAN module by changing a beacon interval and a Delivery Traffic Indication Map (DTIM) interval depending on a state of a portable terminal.
2. Description of the Related Art
Recently, portable terminals having a Wireless Local Area Network (WLAN) function allowing a wireless network access have been introduced into the consumer market. The portable terminal accesses a wireless network through an Access Point (AP) that operates as a bridge and a router between the portable terminal and the network using a WLAN module. The above WLAN function provides better performance than other short distance wireless communication techniques with respect to communication speed. However, since data transmission between the WLAN and the AP may occur at anytime, the power of the WLAN module should always be turned on and maintained, thereby resulting in excessive power consumption.
Accordingly, a Power Save Mechanism (PSM) has been suggested in order to reduce power consumption caused by the WLAN module of the portable terminal. FIG. 1 is a view illustrating the PSM according to the related art. Referring to FIG. 1, a portable terminal that uses the PSM repeats an operation of maintaining an awake state 103 of the WLAN module and switches to a sleep state 105 on a beacon interval 101 basis. More particularly, when a packet to be transmitted/received exists, the portable terminal maintains the awake state 103 without switching to the sleep state 105 by exchanging a Traffic Indication Map (TIM)/ACKnowledge (ACK) packet during the awake state 103. For example, when a packet is to be transmitted from a terminal A 111 to a terminal B 113, the terminal A 111 transmits a TIM packet while in the awake state 103. After the terminal B 113 receives the TIM packet while in the awake state 103, the terminal B 113 transmits an ACK packet to the terminal A 111. Thereby, data communication has been performed by exchanging packets without switching to the sleep state 105. In contrast, a terminal C 115 having no packet to be transmitted/received switches from the awake state 103 to the sleep state 105.
FIG. 2 is a view illustrating a relationship between a beacon and a Delivery Traffic Indication Map (DTIM) according to the related art.
Referring to FIG. 2, a beacon interval 201 and a DTIM interval 203 are shown. Each terminal that uses the PSM maintains the awake state 103 during a relevant beacon interval by periodically selecting one beacon interval in order to receive a multicast or broadcast packet. Here, the selected beacon interval is referred to as a DTIM interval 203. That is, the terminal continues to maintain an awake state without switching to the sleep state during a DTIM interval that repeats at a fixed interval.
While a portable terminal enters a sleep mode because a user's input does not occur within a predefined time, that is, a host processor enters the sleep mode, a probability of receiving a multicast or broadcast packet is significantly reduced. However, the conventional portable terminal performs the PSM of the WLAN regardless of the state of the host processor, and accordingly, power is consumed unnecessarily. For example, the host processor of the portable terminal enters the sleep mode and the probability of receiving the multicast or broadcast packet is significantly reduced. However, since the WLAN maintains an awake state during a DTIM section periodically, power is wasted.